As a method for exposure of a photographic light-sensitive material, an image-forming method due to a so-called scanner process which comprises scanning an original drawing, exposing a silver halide photographic material to light in accordance with the resulting image signal, and then forming a negative or positive image corresponding to the original image has been known heretofore. There are many types of recording devices utilizing such an image-forming method. As recording light sources for these scanning recording devices, a glow lamp, a xenon lamp, a mercury vapor lamp, a tungsten lamp, a light-emitting diode, etc., have heretofore been used. However, these light sources had practical disadvantages in that they have a low output and short life. In order to make up for such disadvantages, there have been developed scanners and laser printers which use a coherent laser source such as a He-Ne laser, an argon laser, or a He-Cd laser as a scanning light source to make exposure at a high intensity of illumination. These scanners and laser printers can produce a high output. However, these scanners and laser printers are disadvantageous in that they are devices of a large size and thereby become expensive, that they need a modulator, and further that the use of visible light restricts the use of safelight for the light-sensitive material, thereby the handling thereof is deteriorated.
In contrast, semiconductor lasers are small and inexpensive. Furthermore, semiconductor lasers can be easily modulated and work longer than the above-described lasers. Furthermore, since the semiconductor lasers emit light in the infrared region, they can use a bright safelight, and thereby the handling thereof is improved. Therefore, the development of a proper light-sensitive material in this field has been gaining in importance in recent years.
On the other hand, silver halide black-and-white photographic materials having been exposed to light are generally processed by steps of development, fixing, and washing or stabilization. When development processing is performed using an automatic developing machine, a replenisher for a developer and a replenisher for a fixer are generally prepared by dissolving the appropriate components constituting each processing solution in water followed by mixing, and the thus-prepared replenisher is reserved in a replenisher tank and fed in a given amount to a developing tank or a fixing tank of the automatic developing machine.
The above-described automatic processing system, including automatic replenishment, is a system established through use for years. However, with the recent development of electronic equipment, the basic system in which silver halide photographic materials are wet processed has been proved to have some disadvantages.
Specifically, the components for each of the developer and fixer are dissolved in water and mixed to prepare a processing solution, and stock tanks for the thus-prepared processing solutions must be provided. Further, although chemical mixers are now widely used, the disadvantage remains that the processing solutions are essentially prepared from several components and extra space is required for a chemical mixer in addition to the space for the automatic developing machine.
In order to make rapid processing possible, an emulsion-hardening reaction is generally performed during processing. However, glutaraldehyde which is usually incorporated in a developer as a hardening agent gives off an irritating smell and also is hazardous in contact with the skin. When hardening is effected by an aluminum salt which is generally used in a fixer, it is necessary to adjust the pH of the fixer to a range of from 4.2 to 4.6, at which the highest hardening reactivity can be attained, in order to suppress swelling with washing water and thereby to lessen the drying load. In this pH range, however, a part of the thiosulfate used as a main component of the fixer decomposes to generate sulfurous acid gas. Also, acetic acid, which is used as a pH buffering agent, produces a gas, thus resulting in contamination of the working environment with unpleasant smells. In some extreme cases, the produced sulfurous acid gas corrodes not only the automatic developing machine but also surrounding equipment through long-term use.
One of the causes of the above-described problems associated with automatic development lies in the hardening reaction during processing, which is usually performed by glutaraldehyde in a developer or an aluminum salt in a fixer. It has previously been known that many of the above problems can be solved by entirely omitting the glutaraldehyde hardening reaction, or by conducting the aluminum salt-hardening reaction, if used, at a pH of 4.65 or higher to reduce its hardening reactivity.
In such a development processing system without a hardening step, it is essential that silver halide photographic materials should be sufficiently hardened in advance. However, if silver halide photographic materials having high sensitivity and high density, such as X-ray films for medical use, are sufficiently hardened beforehand, the required amount of silver coated must be increased, which is unfavorable from the standpoint of conservation of resources and cost.
Therefore, it is a common sense in the art that a higher density is secured by using finely divided grains as much as possible at the cost of photographic sensitivity, i.e., the density per unit amount of silver (covering power) is raised to solve this problem.
Additionally, with the progress of the field of mechatronics, the rapidity in photographic processing combined with such hardware is gaining in importance.
Under these circumstances, it has been keenly desired to sufficiently improve the sensitivity and processing speed in a light-sensitive material processing system for an infrared laser scanner.
In general, a light-sensitive material containing a halide composition having a high chloride concentration can be developed at a higher speed but provides a lower sensitivity. Silver chloride is easily subjected to elution in a developing solution by a sulfite contained therein. This causes precipitation of silver sludge. In order to prevent precipitation of silver sludge, a compound as described in Japanese Patent Application (OPI) No. 24347/81 (the term "OPI" as used herein refers to a "published unexamined Japanese patent application"), U.S. Pat. No. 3,173,789 and British Patent 940,169 may be incorporated into the developing solution. However, the incorporation of such a compound further reduces the sensitivity in the light-sensitive material processing system. That is, this processing system can attain a rapid development and provide a desired gradation but provides low sensitivity.
On the other hand, if the iodide content is high, a high sensitivity can be obtained. However, a high iodide content lowers the development speed and gradation. Therefore, the proportion of iodide is similarly limited.
Furthermore, in order to render to the light-sensitive material a color sensitivity in the near infra-red region, the ratio of the 100 plane to the 111 plane of silver halide grains must be sufficiently high. Also, in order to make this ratio sufficiently high, the proportion of iodide must be limited.
The design of an emulsion for a light-sensitive material having a high sensitivity in the near infrared region is very difficult and thus requires a special technology because this field is new.